Protanthea simplex Carlgren, 1891

(photos of Dirk Schories, Germany: specimens from Sweden, Europe)

Protanthea simplex and a related species Gonactinia prolifera are the only members of the family Gonactiniidae and suborder Protantheae. Protanthea simplex occurs on northern coasts of Europe, sometimes in large settlements especially in places where water turbulence is minimal.